Salesforce buying Slack made absolutely no sense, but I find the comparison to Teams strange. IME orgs use Teams when they're already in the Microsoft ecosystem since there isn't a great argument for purchasing Slack when you already have Teams included in the package you are paying for. If I'm in the market for a Slack-like product I don't look at Teams unless I'm already paying Microsoft.

The real threat to Slack is less from Microsoft and more from Google if they ever launch a Slack-competitor inside of Google Workspaces. I know for my organization even if there wasn't feature parity, we would probably switch just for ease of billing and access control.